Found the first satellite of the planet in another star system
Astronomers at Columbia University (USA) first discovered a celestial body, which is most likely an ex-moon — a satellite of a planet located outside the solar system. The corresponding study has been published in the electronic preprints library arXiv.org, reports the publication New Scientist.
Exolun is located in the orbit of the exoplanet Kepler-1625b. At the same time, the mother star of the latter, Kepler-1625, is located at a distance of about four thousand light years from Earth.
The planet is about two times lighter than Jupiter, orbits around a star with a period of more than 287 days. The satellite, as scientists believe, is comparable in size to Neptune, and is removed from the planet at a distance of 20 of its radii.
The potential exoun is found by analyzing the data obtained by the Kepler space telescope. Scientists estimate the error of observations at 0.006 percent. Experts are planning to check these data in October 2017 using the Hubble orbital observatory. (Lenta.ru)
Or double exoplanet?
Assuming all the above parameters, we can conclude that we can talk about a double planet, if the ratio of their masses is not much higher than 12 (with errors). Then the center of mass of both bodies will be located outside the main planet. The fact is that the removal of two bodies from a common center of mass is inversely proportional to the ratio of their masses, in this case, the ratio of the distances of planets from the center of mass is ~ 1.5 and ~ 18.5 radii of the main planet, respectively. (Note to article)